The US Food and Drug Administration (FDA) has approved 2 screening tests to detect a tickborne parasite in whole and plasma blood supply.

The Imugen Babesiamicroti Arrayed Fluorescent Immunoassay, which detects antibodies to Babesiamicroti in plasma, and Imugen Babesiamicroti Nucleic Acid Test, which detects B microti DNA in whole blood, are the first available screens for Babesia in blood donors. The screening tests can also be applied in living organ and tissue donors.

"The U.S. blood supply remains the safest in the world thanks in part to the FDA's ongoing work to enforce standards for blood collection and to identify and respond to potential threats to the nation's blood supply," said Peter Marks, MD, PhD, director of the FDA's Center for Biologics Evaluation and Research, in a press release. "While babesiosis is both preventable and treatable, until today, there was no way to screen for infections amongst blood donors."

Babesia parasites are transmitted by common deer ticks, with approximately 1000 to 2000 cases reported each year primarily in Northeastern and Midwestern states. Babesia parasites can also be transmitted via blood or blood component transfusion from an infected donor; although bloodborne transmission is relatively uncommon, it is the most frequently reported parasitic infection transmitted via transfusion in the United States.

Most people infected with B microti are asymptomatic, although some will develop influenza-like symptoms, including fever, headache, and body aches. For those with a weakened immune system, infection with B microti can be life-threatening.

The FDA noted that investigational donor testing for Babesia has been underway since August 2012, resulting in the removal of a significant number of infected units of whole blood and plasma from the US supply.

Although there is currently no guidance for the testing of blood samples for Babesia, the FDA plans to release draft guidance for the reduction of risk for transfusion-transmitted babesiosis in the near future.